Design Of Multi-channel Synchronous Data Acquisition System Based On FPGA

Data Acquisition, as an important branch of information science, is a comprehensive technology based on technolgies of sensors, signal measurement and processing and microcomputer. How to realize the denoising, undistorted collection, recording and storage, analysis, processing the small signal, in order to meet the need of different implications, has been the important direction of the data acquisition.As the rearsch background of the rotating machinery vibration signal analysis and fault diagnosis, we put forward a multi-channel synchronous data-acquisition system based on Field Programmable Gate Arrays(FPGA) platform. The fault diagnosis is carried out through the collecting to the signal of the vibration of rotating machinery, performing the time domain, frequency domain analysis, and extracting the signal feature. The main research work includes the following aspects:(1) In terms of the signal processing front-end, we design the circuits of the attenuation, high-pass and low pass filter, the integrating, programmable gain amplifier, anti-aliasing filter, the envelope demodulation. An Analog Devices Company’s 24-bits ADC-AD7765 is selected, the Daisy chain connection mode is adopted to realize the synchronization signal acquisition and serial data output.(2) In terms of data storage, the LabVIEW text IO VI module TXT format file is utilized to perform the data read and write operation. The undertaking waveform recording, data playback functions can be realized as well. At the same time, the large capacity SD card is adopted to store the offline data, which also can be export for more complex analysis.(3) In the aspect of system control, combining with the Verilog HDL and embedded soft core of the Nios II, the FPGA based hardware circuits carried out the controls of the signal parallel acquisition, data storage, data transmission and other complex logic control. These effectively improve the system stability and integration, and greatly reduce the power consumption.(4) In the aspect of data transmission, the use of Ethernet interface technology can achieve the high throughput data transmission. It has the features the strong antiinterference, the advantages of long transmission distance. It can also achieve on line monitoring the equipment operation condition.(5) In terms of computer, the NI LabVIEW virtual instrument platform is adopted, which provides the internal integration professional signal processing module, powerful functions. The time domain and frequency domain analysis are realized, and the results(the signal features, etc.) are directly displayed on the screen.This system has the characteristics of high sampling precision, fast speed, and huge data storage, which can realize multi-channel synchronous data acquisition, also can analysis data and directly display results, etc. The system can be used as an independent acquisition module and, can also perform the data acquisition and analysis by cooperating with the upper computer. We complete the design of the system hardware and software, the hardare installation and debugging, and the preliminary test is undergone. This design can achieve the multi-channels synchronous vibration signal acquisition, storage, and analysis; it also should be applied to other signal acquisition and processing. The design has good application value.